1. Field of the Invention
The invention is related to packet communication technologies, and in particular, to domain and service based update messaging systems and methods for packet based communication networks.
2. Description of the Prior Art
Packet based communication networks package and transmit communications based on packet protocols. Recent advances in packet based communications have resulted in packet based voice communication networks. Voice over Internet Protocol (VoIP) typifies modern packet based voice communication protocols. VoIP networks digitize, compress, and convert voice communications to IP packets. Media gateways extend VoIP calls between and across network domains. Location servers perform call processing to control media gateways, setup and take down calls, and otherwise manage VoIP network operations.
Often times, a VoIP call originates and terminates within the same network domain. In such a case, a gateway is not required for the call. However, when a VoIP call reaches across domains, gateways are utilized to bridge the call between the domains. Gateways perform various functions depending upon the type of domains between which the gateways handle calls. For example, some gateways handle calls between VoIP networks and regions of the public switched telephone network (PSTN). These gateways convert communications to and from packet based protocols and time division multiplexed (TDM) protocols for the PSTN. Other gateways handle calls between separate VoIP networks. These gateways perform border control functions between the various VoIP networks.
Location servers process call requests from VoIP users and determine where and how calls should be routed. Gateways are assigned to specific location servers. Typically, the location servers exchange messaging regarding the status of gateways across the networks. The location servers then update routing tables on the status of the gateways and access the routing tables to determine routes for calls.
In situations where a call remains within a domain, the location servers access a routing table to select a route within the domain for the call. In situations where the call reaches across one or more domains, the location server accesses a routing table to select a first gateway for the call. Another gateway receives notification of the call and accesses its routing table to select either the remainder of the route for the call or to select a second gateway for the call to reach another domain. Some examples of domains include enterprise networks such as a corporate VoIP network. Another example includes a campus VoIP network.
One problem associated with VoIP networks is that, often times, different domains possess different capabilities at different times. For instance, some domains may provide advanced services such as Centrex. However, occasionally the Centrex services go offline or otherwise change status. Some domains offer services such as international calling, whereas other domains do not. For example, a region of the PSTN may include an international switch that provides for connecting international calls. Thus, a gateway that interfaces between a VoIP domain and the switch interworks communications for international calls. However, if the international switch goes offline, there is no mechanism by which to efficiently reconfigure location server routing tables.
Additionally, current location servers utilize a flooding mechanism to update other location servers on the status of media gateways. Such flooding mechanisms introduce a large amount of message traffic that can cause congestion in the location servers. In the preceding example, when a particular domain goes offline, the location server associated with the gateway serving the offline domain floods other location servers with update messages. It would be beneficial for a system to target the recipients of update messages rather than transmitting a flood of update messages.